Motor-driven compressor unit



1953 M. DREWES, JR

MOTOR-DRIVEN COMPRESSOR UNIT Filed Dec. 50, 1947 JNVENTOR. e 922 FEE? i Patented Feb. 24, 1953 UNITED STATES PATENT OFFICE 2,629,539 MOTOR-DRIVEN CQMPRESSOR UNIT Menke DreWe-s, J r., Chicago, Ill., assignor to Payswell Products Corporation, Chicago, 111., a corporatioll of Illinois 2 Claims.

This invention relates to a motor driven compressor unit and more particularly to a compressor unit for use with a self-contained spray gun.

A further object of this invention is to provide a compact and rugged compressor unit for a spray gun assembly which may be useful for a variety of purposes including the spraying of paints, varnishes, lacquers, insecticides-and other chemicals.

An additional object of this invention is the provision of a compressor unit for a spray gun containing two reciprocating pistons driven at high speed by a universal motor under conditions to permit a uniform flow of air to the spray nozzle.

A still further object of this invention is the provision of a pinion and bevel gear arrangement for operating a double piston compressor at high speeds by an electric motor.

Further and additional objects will appear from the following description and the appended claims.

In accordance with one embodiment of this invention there is provided a motor-driven compressor unit comprising a motor having a rotor, a pinion on the forward end of the rotor, a drive shaft support bracket positioned forwardly of the pinion and in substantial alignment with the rotor, a drive shaft mounted for rotation within said bracket extending substantially perpendicular to the longitudinal axis of the rotor, a drive wheel secured to one end of the drive shaft, a combination drive wheel and bevel gear secured to the other end of the drive shaft, and a double piston compressor mounted in spaced relationship to the drive shaft including one connecting rod and piston. driven. by the drive wheel and a second connecting rod and piston driven by the combination drive wheel and. bevel gearv The support bracket is preferably cast integrally with the handle of the spray gun. This arrangement for driving the compressor unit by the electric motor is particularly rugged and permits the compressor to be operated at high speeds in a manner to provide the desired how of air to the spray nozzle of the gun with which it is used.

For a more complete understanding of this invention reference will now be had to the accompanying drawing, wherein:

Fig. 1 is a sectional elevational view of a spray gun constructed with the compressor unit of this invention; and

Fig. 2 is a sectional view taken substantially along the line 2-2 of Fig. 1.

Referring now more particularly to the drawing, there is provided a self-contained spray gun having a handle it, a liquid container l2, an

' released.

electric motor l4 contained within a housing 16, a double piston compressor I8 driven through a suitable gear mechanism contained within a housing forwardly of the motor M. The handle lfi depends from the motor housing l 6 and contains an ordinary electric switch 29 that may be operated by a depressing trigger 22 pivotally mounted within the handle l0 adjacent the front portion thereof. The switch is connected to a suitable source of electricity (not shown) through an electric cord 24 and suitable leads (not shown) extend from switch 21'! to the electric motor 16 to cause the latter to operate when the trigger 22 is depressed in a direction toward the switch 20. The switch is constructed so that the motor will be turned on when the trigger is depressed by finger pressure or otherwise but will be turned off when the finger pressure on the trigger 22 is released. Spring 26 in association with the switch mechanism and springs 28 and 30 in association with the trigger cause the trigger to return to a forward position when finger pressure thereon is It will be understood that upon the release of the trigger the motor will continue to operate until the trigger has returned almost to the limit of its forward position with respect to the forward surface of the handle ii].

The motor I4 mounted within the housing it is of the usual construction and need not be further described in detail. Suffice it to say that it comprises the usual rotor 32, brushes 34 and cooling fan 36 and the necessaryelectrical leads (not shown) extending from the switch 28. The rotor 32 is mounted in the housing within bearings 38 and 40'.

The rotor 32 is provided with a pinion 52 which is keyed or otherwise secured to the forward end thereof for rotation therewith. As shown most clearly in Fig. 2, the pinion 42 meshes with teeth out into the surface of a combined bevel gear and drive wheel 44. The combination bevel gear and drive wheel it is keyed to a drive shaft 55 which extends substantially perpendicularly to the 1ongitudinal axis of the rotor 32, said drive shaft being supported on a support bracket 48 by means of a clip 56 secured to the support bracket by machine screws 52. Between the supportbracket 48 and the clip 50 there is clamped a bearing 5% through which the drive shaft 4:: extend for ro tation with respect thereto. Thus the drive shaft M5 is centrally bearinged within the bearing 5 supported on the support bracket 8 and one end of the drive shaft has the combination bevel gear and drive wheel M keyed thereto. As shown in Fig. 2, a drive wheel 56 is keyed or otherwise secured to the other end of the drive shaft 40. It will be noted that the drive wheel 55 and the combination drive wheel and bevel gear 44 are on opposite sides of and embrace the support bracket 48 which serves as a central support for the drive shaft. It will also be noted from Fig. 1 that the support bracket 48 is cast integrally with the handle I of the spray gun, thus providing a rigid mounting for the drive shaft 46.

The combination bevel gear and drive wheel 44 is connected in the usual manner to connecting rod 58 and piston 60 and the drivegwheel 56 is likewise attached to the connecting rod 62 and is provided with an extension H8 which extends rearwardly toward the handle I0 and the trigger 22. The rear end of the extension I I8 is threaded to a turnbuckle I and the opposite end of the turnbuckle is provided with an aperture I22 through which a pin I24 having an enlarged head I26 is slidably mounted. The head I26 prevents complete withdrawal of the pin I 24 from the turnbuckle I20. The rearward end of the pin I24 is pivotally secured to the trigger 22 at point I28 and a compression spring I30 is provided on the pin I24 which abuts against the trigger 22 and the turnbuckle I20, thus tending constantly to corresponding piston 64. Thus it will be -apparent holdthe turnbuckle and the pin in the relationthat rotation of the rotor 32 will drive the com- 15 ship slfiwndn Fig. l.

bination bevel gear and drive wheel 44 to reciprocate the pistons 60 and 64 which serve as the compressor elements for the compressor I8. It is preferred that these pistons be reciprocated alternately so that compressed air at all times will be forced into a spray nozzle assembly 60. The compressor head of the compressor I8 is provided with air intake ports 68 and I0 for each of the cylinders l2 and I4 and the intake ports are provided with the usual one way flap valves l0 and T8. Each of the cylinders I2 and 14 is also provided with exhaust ports covered with the usual one way flap valves 84 to permit flow of compressed air from each of the cylinders into a compression chamber 88 in the forward end of the compressor.

The nozzle assembly 66 is of a usual type comprising a compressed air passageway 00 communicating with the compression chamber 88 and terminating in a forward portion in an aperture 92 formed in the apex of a conically shaped nozzle tip 94. Thus air within the compression chamber 88 during the operation of the motor I4 continually passes through the passageway 90 at high velocity out of the aperture 92. It is preferred that motor l4 be operated at high speed and, since the total volume of the compression chamber 83 and the passageway 90 is sufficiently large to function as a surge chamber, a substantially uniform stream of high velocity air is delivered through the nozzle 06 of the device.

Beneath the compressor I8 and extending generally in the direction of the handle I0 there is mounted the container I2 which contains the liquid to be sprayed. The container I2 is secured to a nozzle block 96 by a suitable screw thread connector 98 provided with an airtight gasket I00. The nozzle block 96 is provided with a horizontal liquid passageway I02 which communicates with a vertical liquid passageway I04 which latter communicates through a removable dip pipe I06 with the bottom of the container I2. The horizontal passageway I02 is threadably secured in its forward end to a diffuser pipe I08 having a forwardly extending apertured reduced end portion IIO which latter serves as a valve seat for a needle valve II2 extending through the diffuser pipe I 03 and the passageway I02. The needle valve I I2 is reciprocable within the diffuser pipe and the passageway I02 and extends rearwardly from the passageway I02 through a packing plug H4 secured in the rear end of the passageway. A small aperture I I8 is provided in the base of the nozzle block 96 to provide communication between the compressed air passageway 90 and the interior of the container I2 thus providing air pressure within the container for assisting the flow of liquid upwardly through the pipe I06, the passageways I04 and I02 and the dififuser pipe I08.

In the modification shown the needle valve I I2- However, the tension of spring I30 is overcome by the conjoint action of springs 26, 28 and 30 so that when the trigger is completely relieved of finger pressure (a condition not shown in the drawing) then, after the needle valve II2 seats in the valve seat of the diffuser pipe I08, the resistance of spring I30 will be overcome, pushing the enlarged head I26 into the turnbuckle I20. Thereby the trigger is permitted to return beyond a position which corresponds to the seating of the needle valve II2 which is desirable since, in a preferred form of operation of the spray gun, it is desired to have the needle valve seated prior to the time that the switch 20 turns oil the motor I4.

The operation of the device is believed to be clear from the foregoing description of the several operating parts. Thus it will be seen that when the container I2 is at least partially filled with the liquid to be sprayed and the trigger is pulled, the motor will be turned on, causing a substantially constant flow of air through the orifice 92 of the nozzle 86. When the trigger is pulled to its full limit, the pin I24, the turnbuckle I20, the extension H8 and the needle valve I I2 are moved rearwardly to at least partially withdraw the needle valve from the reduced end of the diffuser pipe I08. When this has occurred, the combination of the suction produced at the end of the diffuser pipe I08 by the air flowing through passageway out of the orifice 92 and the pressure against the surface of the liquid in container I2 exerted through passageway I I6 will cause the liquid to pass upwardly through the dip pipe I06 through the diffuser pipe I08. The liquid is thus atomized at the tip of the diffuser pipe and is sprayed from the nozzle 80. When it is desired to discontinue the spray the trigger is released by the operator. Springs 26, 28 and 30 cause the trigger to return toward its forward position. Spring I30 on the pin I24 holds the head I26 against the rear end of the turnbuckle I20 whereby the turnbuckle, extension H8 and the needle valve IIZ are moved to the valve seat in the reduced portion H0 of the diffuser pipe I00. The difiuser pipe is then closed, shutting off the fiow of liquid to the nozzle. After the needle valve I I2 is in its seat, then the trigger continues to move forward by virtue of the springs 26, 28 and 30 to the switch opening position. This further movement is permitted by compression of the spring I 30, causing the pin I 24 to slide forwardly within the turnbuckle I20. Thus it will be observed that the difiuser pipe is closed before the compressed air supply is shut off, whereby the nozzle is automatically cleaned and dripping is prevented when the device is stopped.

It will be apparent from the foregoing that a rugged, compact and easily constructed selfcontained spray gun unit has been provided. It is easily handled and may be readily taken apart for cleaning purposes. It is convenient to onerate and provides a steady but controllable flow of spray at all times during operation and does not have a tendency to drip after the motor has been turned off. Means have been provided for mounting the motor, compressor and associated gear mechanism in such a manner that long life of the device will be insured.

In the foregoing, reference has been made to the combination bevel gear and drive wheel 44 and the drawings show the teeth on the ear extending in directions inclined to the plane thereof. herein employed is intended to include also a face having teeth extending within the plane of or parallel to the plane of the gear.

While one particular embodiment of this invention is disclosed above, it will be understood, of course, that the invention is not to be limited thereto, since many modifications may be made, and it is contemplated, therefore, by the appended claims, to cover any such modifications as fall within the true spirit and scope of this invention.

I claim:

1. A motor driven compressor unit comprising a housing, an electric motor including a rotor therefor mounted within said housing, a pinion disposed within said housing and mounted on one end of said rotor and rotatable therewith, a support bracket disposed within said housing and positioned. in spaced relation with respect to said pinion, said bracket and the axis of said rotor being disposed in substantially coplanar relation, a drive shaft rotatably mounted on said bracket and disposed in substantially perpendicular relation with respect to the plane formed by said bracket and the axis of said rotor, the ends of said drive shaft projecting from opposite sides of said bracket, the axes of said shaft and rotor being in substantially coplanar relation, a first drive wheel disposed within said housing and on one side of said bracket and keyed to one end of said shaft, a second drive wheel and bevel gear combination disposed within said housing and on the opposite side of said bracket and keyed to .the opposite end of said shaft, said bevel gear and pinion being in meshing relation, and a double piston compressor unit mounted within said housing and disposed in spaced relation with respect to said bracket and in substantial alignment with the axis of said rotor; said compressor unit comprising a 7 Ward end of said rotor and rotatable therewith,

However, the term bevel gear as" an elongated support bracket disposed within said housing and having the opposite ends thereof mounted on said housing, said bracket being positioned forwardly of said pinion and in coplanar relation with respect to the axis of said rotor, a drive shaft rotatably mounted on said bracket and disposed in substantially perpendicular relation with respect to the plane formed by said bracket and the axis of said rotor, the axis of said drive shaft being in substantially coplanar relation with respeot to the axis of said rotor, a first drive wheel disposed within said housing and on one side of said bracket and keyed to said shaft, a second drive wheel disposed Within said housing and on the opposite side of said bracket and keyed to said shaft, said second drive wheel having bevel gear teeth formed on the periphery thereof and in meshing relation with said pinion, and a double iston compressor unit operatively connected to said drive wheels and disposed within said housing forwardly of said bracket and in substantial alignment with the axis of said rotor.

MENKE DREWES, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 779,907 Cheshire Jan. 10, 1905 1,070,585 Clarke Aug. 19, 1913 1,4823%? Howe Feb. 5, 1924 1,555,287 Howe Sept. 29, 1925 2,058,225 Brown Jan. 19, 1937 FOREIGN PATENTS Number Country Date 47,26 3 Denmark May 1, 1933 

